The present invention is directed to tapered processing holes for a head suspension in a rigid disk drive and to a method for processing head suspensions using the tapered processing holes.
In a dynamic rigid disk storage device, a rotating disk is employed to store information. Rigid disk storage devices typically include a frame to provide attachment points and orientation for other components, and a spindle motor mounted to the frame for rotating the disk. A read/write head is formed on a xe2x80x9chead sliderxe2x80x9d for writing and reading data to and from the disk surface. The head slider is supported and properly oriented in relationship to the disk by a head suspension that provides both the force and compliance necessary for proper head slider operation. As the disk in the storage device rotates beneath the head slider and head suspension, the air above the disk also rotates, thus creating an air bearing which acts with an aerodynamic design of the head slider to create a lift force on the head slider. The lift force is counteracted by a spring force of the head suspension, thus positioning the head slider at a desired height and alignment above the disk that is referred to as the xe2x80x9cfly height.xe2x80x9d
Head suspensions for rigid disk drives include a load beam and a flexure. The load beam includes a mounting region at its proximal end for mounting the head suspension to an actuator of the disk drive, a rigid region, and a spring region between the mounting region and the rigid region for providing a spring force to counteract the aerodynamic lift force generated on the head slider during the drive operation as described above. The flexure typically includes a gimbal region having a slider-mounting surface where the head slider is mounted. The gimbal region is resiliently moveable with respect to the remainder of the flexure in response to the aerodynamic forces generated by the air bearing. The gimbal region permits the head slider to move in pitch and roll directions and to follow disk surface fluctuations.
In one type of head suspension, the flexure is formed as a separate piece having a load beam-mounting region that is rigidly mounted to the distal end of the load beam using conventional methods such as spot welds. Head suspensions of this type typically include a load point dimple formed in either the load beam or the gimbal region of the flexure. The load point dimple transfers portions of the load generated by the spring region of the load beam to the flexure, provides clearance between the flexure and the load beam, and serves as a point about which the head slider can gimbal in pitch and roll directions to follow fluctuations in the disk surface.
The actuator arm is coupled to an electromechanical actuator that operates within a negative feedback, closed-loop servo system. The actuator moves the data head radially over the disk surface for track seek operations and holds the transducer directly over a track on the disk surface for track following operations.
The head suspensions are typically formed from a sheet of metal using single step or multi-step etching procedures, such as disclosed in U.S. Pat. Nos. 4,235,664; 4,251,318; and 5,846,442. The etching procedure generally includes coating both sides of the sheet material with a photo resist; locating a photo mask on both sides of the metal sheet; exposing the photo resist through the photo mask; developing the photo resist and etching the desired feature. flowever, since suspension components are made by etching simultaneously from both sides of the sheet material, misregistration of the photo mask during exposure causes a shift between the top and bottom of any processing holes in the component. Consequently, the center for the best fit perpendicular cylinder in the processing hole may not align with the center of the processing hole. For example, rather than having a center axis perpendicular to the surfaces of the sheet material, processing holes can be skewed, having a cross sectional shape of a parallelogram rather than rectangular. Consequently, when such processing holes are engaged with a processing tool, such as an alignment pin, the center line of the processing tool will be misregistered with respect to the center line of the processing hole.
Therefore, a need exists for improved processing holes for head suspensions and for an improved method of processing head suspensions using such processing holes.
The present invention is directed to a head suspension for a rigid disk drive comprising one or more tapered processing holes in the load beam. The tapered processing holes can be located in the rigid region, the flexure or the mounting region. The tapered processing holes comprise a first diameter at a first surface of the load beam and a second diameter at a second surface of the load beam, wherein the first diameter is less than the second diameter.
The tapered processing holes are formed by etching. The tapered processing holes comprise side walls forming an angle with respect to a first surface of the load beam of less than about 85 degrees. In one embodiment, the angle is between about 75 degrees and about 85 degrees. The processing hole will comprise a generally conical or frusto-conical shape, although the shape may be asymmetrical due processing variability.
In another aspect of the present invention, a method of processing a head suspension for a rigid disk drive is disclosed. A head suspension is provided having a load beam having a mounting region, a rigid region and a spring region located between the mounting region and rigid region. The head suspension has at least one tapered processing hole comprises a first diameter at a first surface of the load beam and a second diameter at a second surface of the load beam, wherein the first diameter is less than the second diameter. A processing tool is operatively engaged with the tapered processing hole to perform one of mechanically or optically locating, measuring, mounting, and/or aligning a suspension arm or components thereof. A plurality of processing devices can be operatively engaged with a plurality of tapered processing holes.
The processing tool is typically inserted through the first surface into the tapered processing hole. The processing tool can be a tapered processing tool, a straight tool, a machine vision system, or the like.
The tapered processing hole is formed by etching. A photo mask is located along the first and second surfaces of the load beam prior to etching the tapered processing hole.
The tapered processing hole can be used as a reference point for measuring locations on the head suspension. For example, another component can be aligned to the head suspension relative to the location of the tapered processing hole. Alternatively, a tapered processing hole on another component can be aligned with the tapered processing hole on the load beam. For example, a tapered processing hole on a flexure can be aligned relative to the tapered processing hole on the load beam. In another embodiment, a processing device is aligned with the tapered processing hole on a feature forming tool and a feature is formed in the load beam, such as a dimple on the load beam.